Positive drive rotator

ABSTRACT

In a booth in which articles are carried along a pathway for treatment with sprayed material directed through nozzles or the like at the pathway, apparatus is provided for positively rotating the conveyed articles to assure uniform treatment on all sides thereof. Article supports are connected to the conveyer, each having a first portion carried by the conveyer and a second portion rotatable relative to the first portion for holding an article. A toothed member on the second portion is positively engaged by and driven by links of a link belt to rotate the second hanger portion and the article held thereon.

This invention relates to apparatus for conveying articles for treatmentwith sprayed material and more particularly to apparatus including meansto rotate conveyed articles to assure generally uniform treatment on allsides of the article.

In many industrial applications, articles are conveyed through anenclosed booth and treated with fluids or airborne particles directedthereat. Napadow, U.S. Pat. No. 4,207,833 describes one such booth inwhich articles are suspended from hangers carried by an overheadconveyor. The conveyor is protected from the corrosive or contaminatedatmosphere within the booth by a curtain of air which is caused to flowalong the conveyor and prevent spray particles from reaching theconveyor. As is common practice in booths of this type, the material fortreating the articles is sprayed toward the articles from nozzlesdisposed alongside the path of article conveyance, and a continuousairflow pathway is provided in the booth for removing solvent andoverspray from the booth.

Because treatment materials, such as spray coatings, are generallydirected at the articles from one side of the article conveyancepathway, it is preferred in many cases to rotate the articles carried bythe conveyor to assure generally uniform treatment of all sides of thearticle.

As a means of rotating articles within a booth, it is known to providerotatable article carriers associated with the conveyor that are turnedby an elastomeric, flexible belt traveling parallel to the conveyor.Such rotatable carriers may have tires about their rotational axes forfrictional engagement with the traveling belt. The elastomeric belt isdriven at a faster speed than the belt to rotate the articles beingsprayed through a predetermined number of revolutions during theirtraverse of the spray painting nozzles. In other installations, thetires are abutted against a stationary plate and turn as the tires rollalong the plate.

It has been found that a system which relies on frictional engagementbetween a tire and a moving belt has at times failed to assure uniformarticle rotation and treatment to all sides of the articles as a resultof slippage and or sporadic engagement of the belt with the tire.Sporadic frictional engagement results from several causes. The movingbelt has a tendency to throw the tires outward of the belt, i.e., to theside, particularly at high belt speeds, resulting in the tires bouncingalong the belt. Non-uniform wear spots on the belt may also be a sourceof bouncing or slipping of the tires on the belt. If the conveyer and/orbelt are not properly aligned, or if the article carriers are notsuspended in perfect alignment from the conveyer, uneven wear on thebelt may occur and as a result individual tires may be out of contactwith the belt in portions of their travel through the booth. Treatmentsubstance accumulating on the belt and/or tires may reduce frictiontherebetween also resulting in slippage. Thus, the articles may not beturned uniformly or through the described r.p.m. Uneven coating ofarticles, due to poor frictional engagement, may necessitate discard orretreatment of articles, in either case, increasing the cost ofmanufactured articles.

Accordingly, it would be desirable to have apparatus to assure rotationof articles at a predetermined r.p.m. as they are carried through abooth for spray treatments.

It is a general object of this invention to provide an improved systemfor rotating and carrying articles through a spray booth so that wasteresulting from unevenly treated articles is substantially eliminated.

These and other objects and advantages of the invention will become moreapparent from the following detailed description of the drawings inreference to the accompanying drawings in which:

FIG. 1. is a perspective sectional view of the upper portion of a spraytreatment booth having conveying apparatus and article-rotatingapparatus embodying various features of the present invention;

FIG. 2 is an elevational view of the article-rotating apparatus of FIG.1;

FIG. 3 is an enlarged cross-sectional view taken along line 3--3 of FIG.2;

FIG. 4 is an enlarged elevation view of a portion of a continuousengagement chain of the article-rotating apparatus of FIG. 2;

FIG. 5 is an enlarged, horizontal cross-sectional view taken through thebelt and above sprocket engaged in the belt; and

FIG. 6 is a cross-sectional view showing the slide guides for the linkbelt.

As shown in FIG. 1 for purposes of illustration, the invention isemployed in a substantially enclosed treatment booth 10 wherein articlesare treated with sprays of liquids or airborne particles. Typically, thebooth 10 is an elongated building-like structure having vertical sidewalls (not shown), a top wall 14, and end walls 16 to enclose andcontain the environmentally deleterious fluid or airborne particles usedfor treatment.

As a means of exposing a succession of articles 11 to the treatmentsubstance, a conveyer means or conveyer 18 travels within the boothcarrying article support means or hangers 20 that hold the articles 11for conveyance along a pathway through the booth. The conveyer 18 may beof various configurations. The illustrated conveyer configurationcomprises an elongated channel or beam support 22, rollers 24a connectedto ride longitudinally along the support, a flexible chain 26 or thelike which extends longitudinally along the beam support 22 and verticalbars 24 depending from the rollers and having members 25 connected tospaced-apart links on the chain. An appropriate drive (not shown) powersthe conveyer chain 26 and thereby moves the rollers, hangers, andarticles along the beam support 22. Typically, the beam support 22 andconveyer chain 26 are in the form of endless loops allowingunidirectional movement of the conveyer. The conveyor 18 extends beyondthe sides of the booth 10 whereby articles 11 are conveyed into,through, and out of the booth.

To substantially isolate the conveyer 18 and associated apparatus fromthe treatment materials within the booth 10, the conveyer and associatedapparatus are disposed above a main treatment chamber 36 and housed in asubchamber or plenum 30 formed on the top wall 14 of sheet metal orplastic that generally surrounds the apparatus. Only lower hooks 32depending from the hangers extend through a slot 34 in the top wall 14that communicates the plenum 30 with the main treatment chamber 36.

To protect the conveyor, an air curtain or air flow pattern is createdto force air down through the slot 34 and to sweep away paint particlesfrom flowing upwardly into the conveyor and the protective housing 30.Herein, a blower 48 discharges air under pressure into an air plenum 38extending below the blower and along side the conveyor. Slots or holes39 in a plenum wall 40 allow some air to flow into the housing 30 butmost of the air flows through an air discharge slot nozzle 42 in ahorizontal path across the hangers 20 and across the underside of theslot 34.

The positive pressure of air from nozzle 42 is directed across the slot34 preventing the travel of treatment upwardly thereby protecting theconveyer 18 and other mechanisms in the chamber 30 from corrosion ordeposits which would occur if the treatment material were to accumulatethereon.

A plurality of spray means 50, such as spray guns, direct a treatment offluid or airborne particles toward the path of the travel of thesuspended articles 11 through the booth 10. Preferably, the spray gunsare on the side of the booth and direct their spray in the samedirection that the air is discharging from the nozzle 42.

For many applications, it is necessary that the sprayed substance beapplied to all sides of the articles evenly, and, accordingly, thearticle supports 20 by which the articles 11 are supported from theconveyer 18 each have a first portion 52 rotatable relative to a secondportion 54 attached to the conveyer 18, and means indicated generally at56 are provided engaging and rotating the first portion relative to thesecond portion as each article-carrying hangar 20 is conveyed throughthe booth to expose all sides of each article 11 to spray.

In accordance with the present invention, the articles 11 are rotatedpositively through a predetermined number of rovolutions by a positivedrive means 55 preferably located in the protected housing 30 to assuregenerally uniform treatment of the articles by a substance sprayed bythe guns 50 positioned along one side of the pathway. The first or upperportion 54 of each article support 20 is carried along the pathway bythe conveyer 18, and a second or lower portion 52 is journaled forrotation relative thereto and carries a toothed rotable means or spinner62 which is positively driven by a traveling belt or chain 58 in toothedengagement with the spinner 62. The belt 58 has a run 60 parallel to thepathway of the conveyed articles 11 and provides surfaces that arecomplementary to and positively mesh with the teeth 65 of the rotatablespinner 62 carried by the lower hanger portion 52 to positively rotatethe same and articles 11 suspended therefrom. The preferred surfaces toturn the spinners are belt links 66. The traveling belt 58 is driven bya drive 64 to move the engagement belt 58 at a predetermined speedrelative to the conveyer 18, thereby determining the speed at which thearticles 11 are rotated. Typically, the articles are rotated a muchgreater speed than the speed of the conveyor travel and this isaccomplished by driving the belt at a speed substantially greater thanthe speed of the conveyor.

In a preferred embodiment, the rotatable spinner 62 carried by thesupport means is a sprocket wheel having teeth 65 which project intocomplementary spaces 67 between links 66 of the engagement belt 58 withthe links abutting the teeth and forcing them to rotate, as seen in FIG.5. The engagement belt 58 in a preferred embodiment has a plurality ofvertically linked bars or links 66 perpendicular to the plane of thesprocket wheel 62 spaced for engagement with the sprockets thereof. Thedrive means 64 preferably includes a motor 68 connected to theengagement chain 58 providing for rotation of the articles 11 within awide range of rotational speeds. By way of example, the conveyor speedmay be about 20 feet minute which would give about 25 revolutions perminute if the wire belt 58 was stationary. However, the wire belt ispreferrably driven substantially faster than the conveyor belt to give atotal of 80 revolutions per minute to the articles with the speed of thebelt providing the additional 55 revolutions per minute to the 25 r.p.m.due to the conveyor travel.

The upper portion 54 of each hanger 20, in the illustrated embodiment,is a U-shaped bracket 69 connected at its upper ends by a bolt 71 to thevertical connecting bars 24 of the conveyer 18, and a shaft 72, on whichthe lower portion 52 of the hangar is mounted for rotation, is carriedby the horizontal lower segment of the bracket. The shaft 72 is a boltwith its head resting on the horizontal lower bracket segment and itsthread extending through an aperture in the lower segment.

The lower portion of each hanger 20 is mounted for rotation about thethread of the bolt shaft 72 and comprises the sprocket wheel 62 and arigid wire loop 76 suspended therefrom for holding the hooks 32. Thesprocket wheel 62 is rigidified by a large washer 78 along each side,and the sprocket wheels and washers are joined together by the upperends of the loop 76 which extend through aligned apertures in thewashers and sprocket wheels and are welded or otherwise secured therein.A nut 80 at the lower end of the bolt thread retains the lower portionthereon with thrust bearing 73 including low-friction plastic washer,above the sprocket wheel 62 to facilitate rotation of the sprocketwheel.

From each loop is hung one of the elongated hooks 32, each having anarticle-engaging lower end 84 and an upper end 86 that hooks onto thewire loop 76. The elongated hooks 32, which extend through the slot 34between the plenum 30 and main chamber 36, are interchangeable forholding articles at a desired vertical level within the booth accordingto the size of article and the treatment application.

The driving belt 58, which provides the complementary surfaces that meshwith the sprocket wheel 62, comprises the plurality of wire links (FIG.4) or rods 66 having formed ends 90 joined to each other to formcontinuous interlinked loops at opposite ends of the parallel rods. Suchbelts are commercially available, as for example those sold under thetrade name Sani-grid by Cambridge. Preferably, the rods 66 of the chainare formed of a metal, such as stainless steel, which is resistant tocorrosion and which is hard wear resistant material. Rust or othermaterial dropping through the slot 34 would damage the articles 11.

Herein, the drive belt 58 is disposed below the conveyer chain 26 andpositioned so that its rear run 60 engages the sprocket wheel 62 of eachhanger 20 conveyed therealong. The chain links 66 are vertical andperpendicular to a plane through the sprocket wheels 62. Preferably, thehangers 32 are in a plane parallel to the plane of the links 66 in thedriving run 60 as the articles are painted. Because the links are long,the sprocket wheels need not be precisely located at any given heightand they will still mesh with the links. If wear occurs on the links,the sprockets may be shifted vertically to engage other portions of thelinks to increase life of the wire belt.

Positive engagement between the sprocket wheels 62 and links 66 is notaffected by slipperiness caused by accumulation of treatment material onthe surfaces of the links and sprocket wheels. Thus, positive rotationof each article 11 passing through the booth 10 is assured, helping toprovide generally uniform treatment to all sides of each article. Theshafts 92, 94 each carry a pair of sprocket wheels 95 on which theengagement belt 58 is entrained, with its looped ends 90 just above andjust below the sprocket wheels.

The engagement belt 58 and associated drive apparatus are mounted withina rigid frame structure 98 which maintains a relative alignment of theengagement chain 58 and associated drive apparatus. Herein, the frame 98is suspended from a top 100 of the plenum 30 by depending brackets 102.The engagement chain 58 is disposed between an upper frame member 104(FIG. 2) and a lower frame member 106, and shafts 92, 94, between whichthe engagement chain is entrained, extend through elongated slots 108 inthe upper and lower frame members and are mounted for rotation inbearing brackets 110a,b,c,d, above and below the upper and lower framemembers.

The engagement chain driving shaft 92 is mounted for rotation by upperand lower bearing brackets 110a,b (FIG. 2) connected to the supportframe structure above and below the upper and lower frame members 104,106. The driven shaft 94 at the opposite end of the support frame 98also extends through the slots 108 (FIG. 3) of the upper and lower framemember 104, 106, but its upper and lower bearing brackets 110c,d, bywhich it is mounted for rotation, are carried by upper and lower tracks112a,b above and below the frame members, and the driven shaft isslidable along the tracks to move the driven shaft 94 within the slotstoward and away from the driving shaft 92 for adjustment of engagementchain tension and parallel alignment of the shafts.

The driven shaft bearing brackets 110c,d are slid along the tracks112a,b by bolts 114 extending through fixed flanges 115 at the ends ofthe tracks and extending into threaded apertures of flanges 116 on thesides of and integral with the bearing brackets 110c,d. The bolts 114(FIG. 2) are rotatable within but stationary relative to the fixedflange 115, and, as the bolts are turned within the bearing bracketflanges 116, the bearing brackets 110c,d are moved toward or away fromthe fixed brackets adjusting tension and alignment.

In the illustrated embodiment, the motor 68 which powers the engagementchain 58 is mounted in front of the engagement chain on a frame supportplatform 118 elevated above the upper frame member 104. A drive shaft120 of the motor 68 (FIG. 1) extends horizontally into and turns atorque and speed converter 122 which has a sprocket at a output end fordriving chain 125 which is meshed with a sprocket 126 fixed to the upperend of shaft 92.

To assist in guiding the belt links 66 through their travels and with areduced amount of friction, the links 66 may be guided by slides orguides of a friction reducing material such as polyethylene or teflon.Herein, the guides are flat, narrow strips of polyethylene UHMW sold bythe Polymer Corporation. The links 66 have their lower ends 102 restingon thin plastic strip guides 104a (FIG. 6) supported on a horizontal web106a of a bottom angle 107 which has another vertical web 108 spacedoutwardly of the links 66. The strip guide 104a is sandwiched betweenthe lower web 106 and an upper web 110 of a smaller inner angle 112 andis bolted between these webs. An upwardly extending web 114 on the angle112 has a further vertical, lower strip guide 116 secured along itsoutwardly facing side of the vertical web 114. The lower ends of thelinks will slide along the lower guides 116.

Similar upper strip guides 118 are fastened to upper, inner angles 120,and are in vertical planes with the lower strip guides 116. Thus, theupper and lower ends of the links 66 slide along the vertical plasticguides 116 and 118 with little friction. Because the lower ends of thelinks 66 rest on and slide along the respective bottom guides 104a, thelinks 66 travel with a smooth sliding, with very reduced friction intheir travel in their supporting framework.

While the preferred apparatus discloses a conveyer traveling along alinear path, the conveyor may travel through an arcuate or curved path.In some booths, the articles are conveyed in a generally arcuate paththrough about 270° from ingress of the booth. In these arcuate pathbooths, the article supports often project upardly from an underlyingconveyor. These upwardly projecting article supports have a first orlower portion that does not rotate and a second or upper rotatingspindle end on the article support. The upper spindle may have attachedthereto a spinner or toothed wheel for being driven by the linked belt,as above-described, to rotate the articles positively. A suitable aircurtain should be provided to protect the linked belt and conveyor fromthe sprayed particles, as has been described above.

The advantages of the invention should now be more fully appreciated.Articles carried through an enclosed booth for treatment are rotated ata preselected speed which optimizes uniform treatment. Because of thepositive driving of the spinners by the wire belt there is no relativeslippage therebetween and all articles 11 passing through the booth 10are assured of rotation at the preselected speed. Thus, waste due tosporadic rotation, as may occur when frictional engagement is used torotate the articles, is substantially eliminated.

While the invention has been described in terms of a preferredembodiment, modifications obvious to one with ordinary skill in the artmay be made without departing from the scope of the invention. Forexample, while it is preferred that the sprocket wheel 62 engages amoving belt so that the rotational speed may be adjusted, in certainapplications it may be sufficient to provide means, such as a waved orcorrugated wall which engages and rotates the passing sprocket wheels.

Various features of the invention are recited in the following claims.

I claim:
 1. An apparatus including a spray booth for conveying androtating articles, said apparatus comprising:an overhead beam support insaid booth, a conveyor for articles mounted on the overhead beam supportfor traveling therealong during a spraying operation, hanging articlesupports attached to the conveyor and having rotatable lower portionsfor rotating the articles about a vertical axis, toothed members of apredetermined vertical length connected to the rotatable lower portionsto rotate the same at a predetermined number of revolutions per unit oftravel by the conveyor, an endless belt drive means depending from theoverhead beam support and including an elongated endless drive belt, anupper and lower spaced frame members on said belt drive means extendinglongitudinally beneath the overhead beam support, belt sprocketsrotatably mounted in said upper and lower spaced frame members at spacedlocations to rotate about vertical axes, a motor drive connected to oneof the belt sprockets to drive the same at various predetermined speedsto change the number of rotations of the article per unit of conveyortravel, and said elongated endless drive belt having a plurality ofvertically extending elongated rods each of a length several timeslonger in the vertical direction than the predetermined vertical extentof the teeth on the toothed members to allow positioning of the toothedmembers at different vertical heights along the rods to distributeplacement of the toothed members and wear therefrom along the rods inthe vertical direction, a protective housing about said conveyor andsaid upper and lower spaced frame members and having a bottom wallbeneath said endless drive means and said frame members, a slot in saidprotective housing through which depend said article hanging supportswhich are being rotated within said protective housing, and means toblow air through the slot to protect the endless belt drive means andsaid toothed members.
 2. An apparatus in accordance with claim 1 inwhich said motor drive is supported by said overhead beam support andcomprises an overhead motor and a depending drive extending downwardlyto one said belt sprockets to drive the belt.
 3. An apparatus inaccordance with claim 1 including upper and lower plastic guide slidesmounted in the upper and lower frame members and along which slide therods of the belt at a reduced frictional resistance, said lower plasticguides supporting lowers of said rods.